Deco cylinders O2 over pressurized

[lostsheep]

Baker's Dozen for not USing 80/20

I’m not picking sides in the 80% vs 100% but damn, GI3 is a serious d-bag. I can’t believe BAUE hasn’t done a better job distancing themselves from that attitude.

 

[boulderjohn]

I’m not picking sides in the 80% vs 100% but damn, GI3 is a serious d-bag. I can’t believe BAUE hasn’t done a better job distancing themselves from that attitude.

Distance themselves? My impression from the website is that they are clinging to him.

 

[inquis]

A 2000psi fill in an al40 is enough to do all the deco you are certified to actually do.

Unless you're trying to milk two dives out of it.

 

[Wibble]

A couple years ago there was a thread on SB in which people advocating for 80% made their case, and I found it compelling. I myself use O2 for my final deco gas, but I see nothing wrong with using 80%. I think a lot of people were overwhelmed years ago by the bullying attitude displayed in George Irvine III's Baker's Dozen for not USing 80/20 and cannot allow themselves to have any kind thoughts in that direction. If you read that article, understand that it does not address the key benefits to 80/20 and it relies heavily on Irvine's mistaken belief in the oxygen window theory that emphasized doing deco with the highest possible PPO2. The 13th item shows the overall attitude.

GI3 had his opinions and wasn't afraid of using them!

I find 80% more convenient and can get full pressure deco fills when the shops don't have boosters. Most (all?) "recreational" dive shops in the UK don't have high-pressure oxygen, merely whatever's in their delivered oxygen tanks (the large 'J'-sized 50 litre ones) which they use for nitrox blending. Boosters are only really available at the quarries and a handful of technical locations.

Within reason, a full deco gas fill is far more important than getting a partially-full 100% deco cylinder. Fine for one dive, then it needs another fill. Obviously if you want 100% and you have access to boosted oxygen, then fill your boots. If you're diving where boosted oxygen isn't available, then you take what you can get and adjust the decompression plan accordingly.

With that in mind, you play with Multideco and discover that there's no practical difference between 80% and 100% for decompression times (as you get on 80% one stop earlier at 9m/30ft). If your "team" can't work with that then someone's being too dogmatic. It's always better to have a full cylinder of top deco gas than a half-empty one which might not have sufficient for fallback for your "teammate" to complete their deco stop.

BTW, 80% is cheaper for a fill than 100% as there's less oxygen required -- normally pay by the litre/cf.


IMHO 80% deco gas is all about pragmatism.

 

[Wibble]

I’m not picking sides in the 80% vs 100% but damn, GI3 is a serious d-bag. I can’t believe BAUE hasn’t done a better job distancing themselves from that attitude.

Seems GI3 is Mr Dogma. You are not allowed to think. You are not allowed to deviate. You are not allowed to question. You will obey the rules.

Back on planet Earth, diving's about being pragmatic and adapting to circumstances. Didn't someone once mention "The Thinking Diver", which appears to be the polar opposite of GI3's dogma.

Thankfully that's all ancient history.

 

[Imbodie]

At the tech 40/45 level you don't need 3000psi O2 anyway. A 2000psi fill in an al40 is enough to do all the deco you are certified to actually do.

Ok.. Tec-40 limits you to 50% nitrox and 10 minutes of Deco, I see no such limitations for Tec-45.
Not that it matters, this was asked out of general curiosity, not me planning on doing a dive requiring 35 minutes of deco on an AL40.... I mean I don't even intend to plan dives that require any deco, but I have to have the cert to move on to full cave... yes I'll have to do some deco dives to move past tec-40 but not because I just have to stay down that much longer.

 

[elan]

Ok.. Tec-40 limits you to 50% nitrox and 10 minutes of Deco, I see no such limitations for Tec-45.
Not that it matters, this was asked out of general curiosity, not me planning on doing a dive requiring 35 minutes of deco on an AL40.... I mean I don't even intend to plan dives that require any deco, but I have to have the cert to move on to full cave... yes I'll have to do some deco dives to move past tec-40 but not because I just have to stay down that much longer.

At 45 metres you primary deco gas will be 50%. O2 will be the second gas for longer times which you are not interested doing it seems. Handling 2 deco gases requires more training and some experience with one.

Having said that O2 is good for shallower dives say 100ft max past NDL so your question is still relevant. I am not too familiar with tec40/45 course but its strange they do not allow you O2 at the first level as its a perfect deco gas for rec depth dives.

 

[Imbodie]

I am not too familiar with tec40/45 course but its strange they do not allow you O2 at the first level as its a perfect deco gas for rec depth dives.

It is the PADI way... turn one course into TWO... give you 50% at level one and 100% at level two..

 

[inquis]

It is the PADI way... turn one course into TWO

C'mon, they all do for the most part, don't they? You'll pay for Decompression Procedures separately from Advanced Nitrox, regardless of whether they are typically taught together.

 

[inquis]

its strange they do not allow you O2 at the first level as its a perfect deco gas for rec depth dives.

100% takes no prisoners. A bit of margin for the newly minted deco diver seems... prudent.